Trim line problem

Hi all

In the picture below, inside the triangular shape in the middle should be empty.

I tried to trim lines with a curve. I thought CCX and shatter function was used correctly, but nothing happened.

Please suggest possible solutions

Thank you

trim (12.9 KB)
trim lines.3dm (27.2 KB)

Here’s a way using Trim with Region (less bookkeeping than Shatter)

trim lines - (17.3 KB)

Thank you so much Ethan

You can also use this